ProkaGENOMICS 2011 - Abstracts of the 5th European Conference on Prokaryotics and Fungal Genomics, 2011/09/18-21, Göttingen, Germany http://www.prokagenomics.org/
The complete genome sequence of Xanthomonas albilineans provides insights into
pathogenicity of this sugarcane pathogen and allows further assessments of the large
diversity within this species.
Isabelle Pieretti1, Stéphane Cociancich1, Valérie Barbe2, Sébastien Carrere3, Ralf Koebnik4, Patrice Champoiseau1, Arnaud Couloux2, Armelle Darrasse5, Jérôme Gouzy3, Marie-Agnès Jacques5, Emmanuelle Lauber6, Charles Manceau5, Sophie Mangenot2, Mélanie Marguerettaz1, Stéphane Poussier7, Béatrice Segurens2, Boris Szurek4, Valérie Verdier4, Matthieu Arlat8, Dean W Gabriel9, Philippe Rott1, Monique Royer1
(1) CIRAD, UMR BGPI, F-34398 Montpellier Cedex 5, France.
(2) Génoscope, Centre national de séquençage, F-91057 Evry Cedex, France. (3) INRA, UMR LIPM, F-31326 Castanet-Tolosan Cedex, France.
(4) IRD, UMR RPB, F-34394 Montpellier cedex 5, France. (5) INRA, UMR PaVé, F-49071 Beaucouzé, France.
(6) CNRS, UMR LIPM, F-31326 Castanet-Tolosan Cedex, France.
(7) Agrocampus Ouest centre d'Angers, UMR PaVé, F-49071 Beaucouzé, France. (8) Université Paul Sabatier, UMR LIPM, F-31326 Castanet-Tolosan Cedex, France. (9) University of Florida, Plant Pathology Department, Gainesville 32605, U.S.A.
Objectives:
Xanthomonas albilineans is a xylem-invading pathogen that causes leaf scald, one of the major diseases of sugarcane. Previous studies revealed that i/ two important genomic features differentiate X. albilineans from other sequenced species of Xanthomonas: genome erosion and the presence of a type III secretion system (T3SS) of the SPI-1 family (1-2), and ii/ large variability exists among strains of X. albilineans and all strains involved in outbreaks of sugarcane leaf scald disease since the late 1980s belong to the same genetic group called PFGE-B (3). In the present study, we used the genome sequence of X. albilineans strain GPE PC73 to describe all pathogenicity-related features either shared with all species of Xanthomonas or specific to X. albilineans, and to further investigate the large diversity of this species.
Results
Among the major virulence factors described so far in Xanthomonads, most of them are conserved in X. albilineans, except the T3SS of the Hrp family and the gum gene clusters, and Hrp T3SS effectors. The genome of X. albilineans also encodes specificpathogenicity-related factors including twelve non ribosomal peptide synthetases and five enzymes harboring a specific cellulose binding domain. Several DNA fragments present in PFGE-B strains and absent in other strains of the pathogen were isolated by suppression subtractive hybridization (SSH). Additionally, occurrence of methylation of genomic DNA by a specific Dam methyltransferase in PFGE-B strains, but not in other strains, was experimentally demonstrated. Large inter-strain variability in X. albilineans was confirmed using multi locus sequence analysis (MLSA), clustered regularly interspaced short palindromic repeats (CRISPR) and SSH markers.
Conclusions
This study allowed us to identify several new candidate pathogenicity genes. In-depth functional analyses are now necessary to explore the role of these genes in the successful invasion of the sugarcane xylem vessels by X. albilineans.
1. Pieretti et al. 2009. BMC Genomics, 10:616.
2. Marguerettaz et al. 2010. Molecular Plant-Microbe Interactions, 24:246-259. 3. Davis et al. 1997. Phytopathology, 87:316-324.
